The National Fire Protection Agency (NFPA) creates and maintains standards, for example, NFPA 72, which is the National Fire Alarm and Signaling Code and requires field sensitivity and functionality testing of fire detectors on a regular basis. Such testing ensures that contaminants have not built up in a detector or that a detector has not been exposed to contaminants that may affect the detector properly detecting fire.
Field sensitivity and functionality testing is different than functional or go/no-go testing, which can be performed via a test switch on a detector or via an unmeasured concentration of an ambient condition that can be sprayed into a detector. For example, functional or go/no-go testing only verifies that a detector is capable of generating an alarm, that an ambient condition can enter a sensing chamber, and that a detector can notify a fire alarm control panel about an alarm. However, functional or go/no-go testing does not verify the sensitivity or proper alarm level of a detector.
Test devices for conducting field sensitivity and functional testing on fire detectors are known in the art. A single criteria fire detector can be responsive to a signal from a single type of sensor such as, for example, a smoke sensor, a heat sensor, or a gas sensor, such as a carbon monoxide sensor. Accordingly, a test device for a single criteria fire detector can expose the detector to a known concentration of a single ambient condition to initiate an alarm in the detector.
For example, some known testing devices include an aerosol generating device and a cup that can be placed over a detector. The generating device can generate a known concentration of an ambient condition, such as smoke, heat, or gas, which can be directed to the detector via the cup. Upon detecting an amount or concentration of the ambient condition above a predetermined threshold, the detector can initiate an alarm.
Unlike with single criteria fire detectors, it is difficult to test the field sensitivity and functionality of multi-criteria fire detectors because such detectors use complex algorithms to combine signals from multiple sensors, such as, for example, a smoke sensor, a heat sensor, and a gas sensor, such as a carbon monoxide sensor, to determine when to initiate an alarm. Accordingly, exposing a multi-criteria fire detector to only a single ambient condition, as when testing a single criteria fire detector, may not initiate an alarm in the multi-criteria fire detector.
Test devices for multi-criteria fire detectors are known and can generate a plurality of different ambient conditions, such as, smoke, heat, and gas, but such devices may not generate the ambient conditions in a combination and at such as rate so as to initiate an alarm in a fire detector. Indeed, known test devices may not know the combination and rate of ambient conditions required by an algorithm used by the detector to initiate the alarm. Furthermore, different manufacturers of fire detectors may use different algorithms to combine signals from multiple sensors. Accordingly, a test device that works for one fire detector may not work for another fire detector.
In view of the above, there is a continuing, ongoing need for improved test devices.